A tunable laser is one in which the wavelength may be varied over time in a predictable manner. In the past, conventional tunable lasers have utilized mechanical movement as the basis for wavelength tuning. Such mechanical movement may be induced by a number of devices including, for example: a grating that may be tilted to generate different wavelength reflection into the laser cavity; a mircoelectromechancial (MEMs) device that deflects to generate the wavelength change; and a filter that may be tilted to generate the wavelength change.
A new category of tunable laser based on an all-electronic tuning mechanism is now being utilized, which can tune without mechanical movement. These akinetic lasers have many useful qualities, including high speed, flexible tuning, and good optical quality. Lasers of this type have so far all been based on a semiconductor structure similar to the sample grating distributed Bragg reflector (SG-DBR), or sampled grating distributed Bragg reflector.